In dyeing machines of the type in which a textile web, e.g. a yarn, in rope form is dyed by circulating the web through a liquid dye so that a collection of the web accumulates in a storage zone of the path through the machine, it is possible that the continuous advance of the web may be interrupted by a blocking of the loops of the web which are formed.
In such a machine, the textile workpiece may be a hank of yarn, braid, woven or other tubular material, closed on itself and may be guided repeatedly through the bath of dye disposed at the lower part of the machine. At some point along the path, a storage zone can be formed, e.g. in the bath at the lower part of the machine, in which storage of the web is effected in the form of accordion folds or loops, a strand emerging from this zone and extending through the upper zone of the machine, passing into contact with the guide means or entrainment means which may be provided in this upper zone.
The web is thus continuously displaced and he accordion folds are reformed in a region at which the descending strand enters the storage zone which, as noted, may contain the bath of dye.
The machine of this type is described in my U.S. Pat. No. 3,971,236, for example.
The textile material or rope forming the web may be any dyeable material and, while a hank of yarn may be a preferred workpiece to be dyed, knitted or woven fabrics, preferably tubular fabrics, may be dyed in a similar manner. All of these materials will be included in the term web" as this term is used herein.
The means for entraining the web through the machine can include a motorized roller or reel mounted in an upper part of the machine and can include means for holding the web against this roller or reel. It also may comprise nozzle means for pneumatic transport of the web or even a combination of nozzles and rollers or reels for a combined pneumatic and frictional or positive displacement.
The fabric stored in the storage zone of the machine, however, acts as an obstruction in many cases to the oncoming web and thereby disturbs the optimum positioning of the accordion folds and the like. In addition, an oscillation can develop in the stored portion of the web which can contribute to disturbance of the stored quantity to the point that withdrawal of the web can be blocked.
Such blockage can give rise to dyeing defects and can be prejudicial to the quality of the finished product.
While this problem is particularly significant in the case in which the displacement of the web is effected only pneumatically by air jets from respective nozzles, because ascent of the web is prevented and the force generated by the pneumatic displacement medium cannot overcome the resistance to circulation of the fabric, it is also a problem with reels and the like which exert mechanical traction upon the web.